The present invention relates to roll cleaning systems, and more particularly to apparatus for an automatic self adjusting roll cleaning system.
Sheet stock, such as steel, plastic, aluminum and paper, is generally fed through a series of rolls, such as guide rolls and wringer rolls, as part of the manufacturing process. Such rolls serve to provide contact with the sheet stock for a variety of purposes, such as to guide or dry the sheet stock either before or after a coating process, as it is being cut to width, or as it is wound into large coils for ease of handling, storage and transportation. The surfaces of such rolls have a tendency to accummulate abrasive contaminants, corrosive coatings and particles of sheet stock on their surfaces, which can seriously mar and damage the surface of the sheet stock. Furthermore, such accumulations on the roll surfaces may embed themselves in the roll surfaces, scar the roll surfaces, or otherwise seriously damage them. It is therefore desirable to clean the surfaces of the rolls to prevent such accumulations from damaging both the sheet stock and the rolls themselves. Although it is possible to shut down a manufacturing operation to periodically change the rolls with fresh ones that have been cleaned, or to manually clean the rolls in service, it is generally uneconomic to do so, because the down time involved to stop and start the manufacturing operation is excessive.
Consequently, roll cleaning apparatus which functions during the manufacturing process is preferred. One such cleaning system in the prior art has been devised and developed by the Applicant of the present invention. This cleaning apparatus comprises a series of polishing blocks arranged on a polishing block support assembly in a tandem block arrangement having a total combined width at least as wide as the roll surface, and mounted tandem to a lever operated engagement system so that the operation of the lever engages the polishing blocks over the entire width of the roll surface. The polishing blocks are each resiliently mounted so that they each provide substantially the same surface pressure within a wide range of variation of polishing block wear between the different polishing blocks. However, their cleaning system is not completely satisfactory because the stationary polishing blocks so used have a tendency to leave a scarring pattern of their own.
An improved roll cleaning apparatus is described in U.S. patent application Ser. No. 193,596 entitled "Apparatus for Cleaning and Polishing Roll Assemblies", filed May 13, 1988, now U.S. Pat. No. 4,841,675, issued June 27, 1989 also to the Applicant of the present invention. This apparatus automatically engages and oscillates the tandem arrangement of polishing blocks described above on the roll surface. The oscillating motion of the blocks laterally scrub the roll surface as they polish to prevent any polishing block scarring pattern to develop. The oscillating feature of this apparatus is secured with a pneumatically actuated positioning cylinder for one end of the tandem polishing block arrangement on its polishing block support assembly and a hydraulically operated dampening cylinder for the other end. Each of the cylinders is individually supported into position with its own pneumatic support assembly. This arrangement provides automatic alignment of the polishing block support assembly with the roll surface at a regulated pressure. Furthermore, separate cylinders for each end of the polishing block support assembly prevent bearing misalignment problems.
Although this apparatus is very satisfactory from the standpoint of performance, it is bulky, complex and expensive. A roll cleaning apparatus which has a simpler polishing block engagement system, combined with a simple single ended positioner for reciprocally oscillating the polishing block support assembly, is more suitable for many applications with restrictive economic or physical space requirements. However, a simple end driven block support assembly requires some sort of means for preventing axial misalignment during operation, or alternatively, some means for successfully operating with large amounts of axial misalignment.
A major limitation of axial misalignment tolerance for axially reciprocating systems is bearing design. Although various bearing designs allowing axial motion are known which have a certain amount of either rotational freedom of movement about a point, or lateral freedom of movement relative to an axis, there are none that have a tolerance for both rotational and lateral misalignment combined.